In wireless communication, information is transmitted using a radio communication channel. To perform the transmission, a useful signal comprising the information is modulated on a RF carrier signal to produce a modulated RF signal and fed by an antenna into the radio communication channel. The modulated RF signal propagates through the radio communication channel and is subsequently received as received RF signal by a receiver apparatus. The receiver apparatus is disposed to process the received RF signal in order to reconstruct the useful signal.
Current trends in mobile communication are facing industry with a demand of high data rate applications. These may be, e.g., video telephony, video or network games, streaming multimedia, web browsing, etc. In consequence, telecommunication devices are being arranged for multi-band and/or multi-mode operation. Communication standards allowing for a high data rate transmission, such as HSDPA (High Speed Downlink Packet Access) or HSUPA (High Speed Uplink Packet Access) are being developed within the established UMTS (Universal Mobile Telecommunication System) or W-CDMA (Wideband Code Division Multiple Access) standard. Other standards are defined by WLAN (Wireless Local Area Network) within IEEE 811.11 or by WIMAX.
High data rate usually require for a good signal quality in a receiver apparatus, i.e. a relatively high Signal-to-Noise-Ratio (SNR) in a receiver chain of both, a terminal device—such as a mobile phone—and in a base-station. With increasing distance between a transmitter apparatus and a receiver apparatus, the received RF signal may be distorted with respect to the modulated RF signal.
If the terminal device is close to the edge of a cell surrounding a base-station, reception quality in the receiver apparatus is limited by thermal noise and a noise figure of the receiver apparatus itself. Furthermore, the received RF signal is distorted by a noise figure of the radio communication channel, which is caused by mechanism such as Rayleigh fading, thermal noise of other electronic devices, man-made noise, e.g., caused by automobile ignition, any natural noise, e.g., electric discharges, such as lightning, etc.
A possible solution to achieve high data rate would by an increase of a number of base-stations, so to minimize a maximum distance between a terminal device and a base-station. Yet, this requires a high financial investment into a base-station infrastructure.
Another possible solution is an increase of the number of reception paths in the receiver apparatus. In consequence, a more accurate reconstruction of the useful signal may be achieved. This concept is also denoted as “diversity receiver”. A diversity receiver usually requires a number of internal components in the receiver chain, and it is desirable to reduce that number to provide for a simple and more cost-efficient architecture of a diversity receiver.
For these and other reasons, there is a need for the present invention.